This invention relates to sanitary napkin provided with a pair of wings.
It is well known to provide a sanitary napkin with a pair of wings by bonding its topsheet and backsheet to each other, for example, from Japanese Patent Application Disclosure Gazette (Kokai) No. Hei7-303670. It is also well known that a breathable and liquid-impervious plastic film is sometimes used as material for a backsheet of a sanitary napkin. For example, extruded a film obtained from a mixture of polyethylene and fine particles of barium sulfate or calcium carbonate may be stretched to make such a plastic film.
The breathable/liquid-impervious plastic film made from foregoing mixture has a relatively low tear strength and therefore the wings formed by using the film as the backsheet has sometimes been torn at its proximal end longitudinally of the napkin as the wings are pulled to peel off the used napkin from the wearer""s undergarment. While the topsheet may be bonded to the film as reinforcing means to improve the tear strength of the wings, the breathability of the film will be adversely affected in the regions of these wings depending on the manner of bonding. The wings are not necessarily folded, over their entire areas, onto the outer surface of the undergarment but sometimes partially left on the inner surface of the undergarment in contact with the wearer""s skin. The wings sometimes partially left on the inner surface of the undergarment must be free from the concern that the particular manner of bonding might deteriorate the breathability of the film.
It is an object of this invention to provide a sanitary napkin having a pair of wings formed by a breathable/liquid-impervious backsheet so that a tear strength of the wings can be improved without deterioration of its breathability.
According to this invention, there is provided a sanitary napkin provided with a pair of wings, the sanitary napkin comprising a breathable/liquid-pervious topsheet, a breathable/liquid-impervious backsheet and an absorbent core disposed between the topsheet and the backsheet, the wings comprising a portion of the backsheet extending bilaterally of the napkin and a sheet material bonded to the bilaterally extending portion and said wings being formed on surfaces of the wings intended to be placed upon an undergarment with adhesively fastening zones, and the sheet material being of a breathable nature and bonded to the portion of the backsheet extending bilaterally of the napkin as well as to respective proximal ends of the portion by means of bonding lines extending in a transverse direction of the napkin and arranged intermittently in a longitudinal direction of the napkin.
According to one embodiment of this invention, the sheet material is a part of the topsheet.
According to another embodiment of this invention, the wings are coated with adhesive agent so as to describe a plurality of spirals and the bonding zones are substantially defined by portions of the spirally coated adhesive agent extending in the transverse direction of the napkin and arranged intermittently in the longitudinal direction of the napkin.
According to still another embodiment of this invention, an area percentage of the bonding zones occupying the wings is in a range of 3-60%.
According to further another embodiment of this invention, the napkin has a bonding line formed by heat-sealing to bond the topsheet and the backsheet along a periphery of the napkin and extends, in the vicinity of the respective proximal ends of the wings, in parallel to transversely opposite side edges of the absorbent core so that the sheet material is bonded to the backsheet also along the bonding line.